2,681 reputation
518
bio website www34.homepage.villanova.edu/…
location Centro Habana
age 57
visits member for 2 years, 4 months
seen Feb 18 at 18:10

Haverford (mental institution) MIT (yet another) Tufts, Univ. of Utah (in East Berlin), Rutgers (near East Berlin, NJ), Villanova, Notre Dame, Univ. of New Hampshire, Hostos-CUNY, Queen's Univ. (Canadá).


2d
awarded  Nice Answer
Feb
16
answered Does entropy apply to Newton's First Law or does “acted upon” always require an external factor?
Feb
15
comment Does entropy apply to Newton's First Law or does “acted upon” always require an external factor?
@JerrySchirmer The OP is asking about the validity of the Law for non-closed systems. Look at the quote. The OP wants to know if «all objects» really are «slowing down» because of entropy increase. (Because they are not the whole Universe and so are not closed systems). The question is hard because neither Newton's Laws nor the Second Law of Thermodynamics apply except to closed systems, but the OP is asking about open systems.
Feb
14
comment Does entropy apply to Newton's First Law or does “acted upon” always require an external factor?
@JerrySchirmer This answer is correct physically but neglects the point of the question. The OP takes it as given that nothing is precisely a closed system except the Universe as a whole. «all objects though, since they are all in the closed system of the universe at large, and therefore they are all subject to slowing down...» so instead of fighting the hypo we should address the physical situation envisaged in the OP: non-closed systems. Imperfect vacua...
Feb
14
awarded  Necromancer
Feb
13
comment Should I heat my room when I'm not here, energy-efficiently speaking?
Consumer Reports addressed this question, and also about a/c, many years ago. The set point of the thermostat must not be altered by more than double-digits or you lose more in restoring livability. Experiment is the key to ansering this question
Feb
10
comment Why does my refrigerator door resist opening?
The manual that came with the fridge said so.
Dec
31
awarded  Necromancer
Dec
1
awarded  Yearling
Nov
29
revised What happened with Hilbert's sixth problem (the axiomatization of physics) after Gödel's work?
added Part III to clarify some of the issues involved in comments etc.
Nov
29
comment What happened with Hilbert's sixth problem (the axiomatization of physics) after Gödel's work?
let us continue this discussion in chat
Nov
29
comment What happened with Hilbert's sixth problem (the axiomatization of physics) after Gödel's work?
To answer the question, about gravity, the axiomatisation of Mechanics which Hilbert thought of as a good example did not include the law of gravity, it only included Newton's Three Laws of Motion and his definition of Force. It also used a non-Euclidean geometry on phase space to formulate a least curvature principle (Hertz). So, as a matter of fact, we do ignore Newton's law of gravity in this subject, even back when we thought it was true (Hertz did this before Einstein). Hilbert had a strange ontology for Maths, but in Physics his ontology was normal, and not axiomatic.
Nov
29
comment What happened with Hilbert's sixth problem (the axiomatization of physics) after Gödel's work?
In the context of Hilbert's problem, we are to take the model as being exact and deduce its consequences stricly logically. In the context of the Theory of Everything, there are still some physicists...perhaps not too many...like Steven Weinberg, who hope to get an exact theory. In the context of applying the results of the theory of computation, since they are mathematical deductions, we don't know if they remain valid if the mathematical model is merely an approximation. They're only valid if the model is exact. The conclusions aren't robust. A revision will emphasise these points.
Nov
28
comment What happened with Hilbert's sixth problem (the axiomatization of physics) after Gödel's work?
I addressed «qubits» when I pointed out that all idealisations of computing machines are unphysical. This applies to qubits as well. When I say most physicists, I exclude Zeilinger. The decoherence approach, although I do not agree with it, is quite widespread, a little vague, and not (yet) the consensus. But as I understand it, the decoherence approach agrees in deducing quantum randomness from Schrodinger's equation. If something like this is not accomplished, then I pointed out that Wigner's critique of the axiomatisation of QM would indeed be decisive: the axioms would be inadequate.
Nov
28
revised What happened with Hilbert's sixth problem (the axiomatization of physics) after Gödel's work?
added Part II to address OP specific concerns
Nov
28
comment Can we construct Axiomatic system of physical laws?
In the three fundamental axioms of QM, the only function that occurs is the exponential of the Hamiltonian. If the Hilbert Space is finite dimensional, then this is obviously computable in either sense. So, for the sake of discussion, let us assume that infinite dimensions are not a problem. In other comments and answers you have been clear that you think it is necessary to include the axioms of logic, as well, so you throw in PM, all the functions are still computable... and now what?
Nov
28
comment Can we construct Axiomatic system of physical laws?
Your clarification still leaves me in the dark as to your meaning. An axiom is not a function. An axiomatic system consists of primitive concepts and axioms. The axioms are certainly not functions. The primitive concepts might be. But in, say, Hilbert's axiomatisation of Euclidean Geometry, I am not sure I remember any functions. And, to go to the opposit extreme, Principia Mathematica has functions but surely they are all computable? negation, etc.? so what this has to do with consistency is still a mystery to me. I'd have thought computable systems are simpler than uncomputable ones....
Nov
28
comment Can we construct Axiomatic system of physical laws?
In a properly formulated Theory of Everything, questions like «Do I exist?» should be impossible to formulate. IN fact, the pronoun «I» should have no translation into Physics, nor should the verb «exist». (Kant: existence is not a predicate.) It's not an accident that their use in textbooks is rather rare.
Nov
28
comment Can we construct Axiomatic system of physical laws?
There is a subtle difference between computable as used in maths, and computable as used in Physics. If I understand the difference, it is that in maths, the same algorithm must be capable of giving the answer to any desired degree of approximation. But in Physics, we do not care whether a different algorithm would be needed for each different case. This is like the difference between omega-consistency and consistency. There might not be an algorithm within the system for producing the new and different algorithm needed for each case. So, I am not sure how to answer your question.
Nov
28
comment Does Gödel preclude a workable ToE?
Goedel himself proved that first-order logic was consistent and decidable. Am I missing something here? You keep asserting Goedel's conclusions without what I understand as an essential hypothesis: it has to include Peano arithmetic, more specifically, the principle of mathematical induction. First-order logic does not include this, and neither (afaik) does Euclidean Geometry.